Senior Cyber Security Engineer

Job summary

About us
MI5 keeps the country safe from serious threats like terrorism and attempts by states to harm the UK, its people and way of life. We carry out investigations by obtaining, analysing, and assessing intelligence, and then work with a range of partners including MI6 and GCHQ to disrupt these threats. Through our protective security arm, we provide advice and guidance to government, businesses and other organisations about how to keep themselves safe. A role in MI5 means you'll do unique and challenging work in a supportive and encouraging environment, making a real difference to UK national security.

Job description

As a Senior Cyber Security Engineer, you'll play a central role in protecting the organisation's digital products, embedding security into how systems are designed and built. The role combines engineering and security expertise, applying practical skills to identify weaknesses, validate controls and help teams deliver secure, resilient systems from the outset.

Working within a highly collaborative environment, you’ll contribute to organisation-wide security capability, tackling complex challenges across a diverse and evolving technology landscape. Early engagement in the development lifecycle is vital, shaping design decisions, influencing architecture and ensuring security is integrated into modern engineering practices.

This role combines technical depth with real influence. Threat modelling, vulnerability assessment and security testing form a core part of the work, applying an adversarial mindset to uncover risks. Just as important is working directly with engineers, architects and stakeholders to resolve those risks, improve practices and raise the organisation's overall security maturity.

You’ll take a "purple team" approach, combining elements of red team testing and defensive security – identifying vulnerabilities and working with teams to fix them, building better, more secure systems.

The role also extends to the wider direction of security engineering: supporting less experienced colleagues, influencing technical decisions and helping stakeholders understand risk, trade-offs and priorities. With a high degree of autonomy, you'll take ownership of complex problems and play a key role in how security is delivered across the organisation.

Person specification

You’ll bring practical experience in a security-focused role, such as cyber security engineering, penetration testing or a closely related technical discipline. This could be supported by a STEM degree with relevant experience, or a technical role with a strong security focus.

Experience with real-world systems is essential, identifying and solving security issues, alongside a solid understanding of core security principles such as Secure by Design. You'll have applied techniques such as threat modelling, vulnerability assessment or security testing, and be confident thinking critically about how systems can be exploited and secured.

You communicate clearly with both technical and non-technical stakeholders and are comfortable working collaboratively to resolve issues. Curious and pragmatic, you’re motivated to keep learning and apply your expertise to complex, high-impact challenges.

Benefits

Training and development

From the moment you join, you’ll be supported to develop your expertise in cyber security through a blend of hands-on experience and structured learning. You’ll work closely with experienced colleagues across a range of security challenges, gaining exposure to different systems, tools and approaches.

A wide range of development opportunities is available, including on-demand learning platforms, virtual cyber ranges and formal training aligned to your role. There is also support available to achieve industry-recognised certifications, such as SANS (The Sans Institute), GIAC (Global Information Assurance Certification), CISSP (Certified Information Systems Security Professional Qualification) or Offensive Security qualifications, alongside opportunities to attend UK-based and international security conferences.

As you grow in the role, you’ll take on increasingly detailed work, building both technical depth and influence, with the support of your team, mentoring opportunities and exposure to real-world threat intelligence.

Rewards and benefits
You’ll receive a starting salary from £64,005 to £66,332, depending on location, plus other benefits including:

• 25 Days Annual Leave automatically rising to 30 days after 5 years' service, and an additional 10.5 days public and privilege holidays
• opportunities to be recognised through our employee performance scheme
• dedicated development budget
• interest-free season ticket loan
• excellent pension scheme
• cycle to work scheme
• facilities such as a gym, restaurant, and on-site coffee bars (at some locations)
• paid parental and adoption leave

Things you need to know

Artificial intelligence

Artificial intelligence can be a useful tool to support your application, however, all examples and statements provided must be truthful, factually accurate and taken directly from your own experience. Where plagiarism has been identified (presenting the ideas and experiences of others, or generated by artificial intelligence, as your own) applications may be withdrawn and internal candidates may be subject to disciplinary action. Please see our candidate guidance (opens in a new window) for more information on appropriate and inappropriate use.

Selection process details

Before you apply
To work at MI5, you need to be a British citizen or hold dual British nationality. Read about our eligibility criteria.

This role requires the highest security clearance, known as Developed Vetting (DV). It’s something everyone in the UK Intelligence Community undertakes. Find out more about the vetting process.

Please note we have a strict drugs policy, so once you start your application, you can’t take any recreational drugs and you’ll need to declare your previous drug usage at the relevant stage.

Before you apply, we advise you to consider setting up a separate email address for your contact with us, to ensure your personal and application correspondence remain separate. Try to avoid having identifying features in your email address, such as your first and/or surname and date of birth. This is good practice and will help you manage your application with us more discretely.

The role is based in London or Greater Manchester so you’ll need to live within a commutable distance. Please consider any financial implications and practicalities before submitting an application, as we do not offer relocation costs.

We offer reasonable reimbursement of travel costs for candidates attending in person appointments during the recruitment and vetting process. Full details will be provided with your interview or assessment invitation.

Reimbursement is discretionary and will only be made in line with the Candidate Expenses Policy, as amended from time to time. Candidates must book their own travel, using the most economical option, and provide original hardcopy receipts for reimbursement.

Please note, you should only launch your application from within the UK. If you are based overseas, you should wait until you visit the UK to launch an application. Applying from outside the UK will impact on our ability to progress your application